On the thermodynamic aspect of zinc oxide polymorphism. Calorimetric study of metastable rock salt ZnO

TL;DR

This study measures the enthalpy of dissolution of zinc oxide polymorphs to determine the thermodynamic properties of the phase transition between metastable rock salt and stable wurtzite forms.

Contribution

It provides the first direct calorimetric measurement of the enthalpy change for the rock salt to wurtzite phase transition in ZnO.

Findings

Enthalpy of dissolution for rock salt ZnO measured at 303 K.

Enthalpy of dissolution for wurtzite ZnO measured at 303 K.

Standard enthalpy of phase transition determined as -11.7 kJ/mol.

Abstract

The enthalpies of dissolution of metastable rock salt and thermodynamically stable wurtzite polymorphs of zinc oxide in aqueous H2SO4 have been measured in direct calorimetric experiments at 303 K and 0.1 MPa and the obtained results enabled determination of the standard enthalpy of the rock salt-to-wurtzite phase transition in ZnO, {\Delta}trH = -11.7+/-0.3 kJ/mol.